EP2460241B1 - Broad stripe laser having an epitaxial layer stack and method for producing the same - Google Patents

Description

The present invention relates to a broad strip laser with an epitaxial layer stack containing an active radiation-generating layer. Furthermore, the invention relates to a method for producing such a wide-band laser.

Semiconductor lasers, due to their compactness and cost-effective production, find application in numerous fields of application, such as data transmission, data storage, projection, material processing, optical pumping, biosensing and the like. In particular, semiconductor lasers based on the AlInGaN material system offer a wide variety of possible uses due to their generated radiation in the UV to blue-green wavelength range. In most applications, it depends on a high optical output power or output power density of the semiconductor laser.

However, in semiconductor lasers, the output power is limited due to thermal effects. For example, in so-called "single emitters" the output power is limited to a few 100 milliwatts in cw mode.

Among other things, optical output powers can be increased by increasing the efficiency of the semiconductor laser, for example by means of an optimized epitaxial design of the layers of the semiconductor laser. However, this is also here limits the output power of such semiconductor lasers due to thermal effects to a few 100 milliwatts in cw mode.

Performance enhancing measures can also be made possible, for example, by the simultaneous operation of multiple laser diodes.

In addition, in the case of wide-band lasers, the so-called "thermal lens", which causes the laser mode to constrict to a few μm at high currents, runs the risk of damaging or even destroying the webs arranged at the top at high current densities.

The publication GB 2 180 690 A relates to a semiconductor laser array.

In the publication US 2009/0092163 A1 For example, a laser diode and method of fabrication is disclosed.

A strip diode laser can be found n the publication US 5,299,219 A ,

The description of a semiconductor laser is in the document JP 2007-157906 A played.

In the publication US 4,400,813 A a laser with a strip waveguide is disclosed.

The publication GB 2 388 958 A is to take an optical component.

A semiconductor laser array is from the document JP 01-175281 A known.

The invention has for its object to provide an improved wide-band laser, which in particular has an improved optical power density, increased efficiency at high power and improved life. Furthermore, the invention has for its object to provide an improved, in particular simplified manufacturing method of such a wide-band laser.

These objects are achieved by a wide-band laser having the features of patent claim 1 and a method for its production having the features of patent claim 15.

According to the invention, a wide-strip laser with an epitaxial layer stack is provided which contains an active, radiation-generating layer and has an upper side and a lower side. The layer stack has trenches in which at least one layer of the layer stack is at least partially removed and which lead from the top toward the bottom. The layer stack further has webs on the upper side, which each adjoin the trenches, so that the layer stack is strip-shaped on the upper side. The webs and the trenches each have a width of at most 20 microns. Preferably, the webs and the trenches each have a width of at most 10 .mu.m, more preferably of at most 7 .mu.m.

Accordingly, such a broad-band laser preferably has index-guided, closely adjacent individual strips, so-called webs, with a width of less than 20 μm, on the upper side, preferably less than 10 μm, more preferably less than 7 μm. Adjacent webs have a distance of at most 20 microns, preferably of at most 10 microns to each other.

The wide strip laser according to the invention thus does not have, as is the case on the upper side, only a wide strip. In particular, according to the invention, the broad stripe of the laser is split up into individual strips, the so-called webs.

Such broadband lasers advantageously have an improved, in particular increased optical output power and output power density with simultaneously reduced facet load. Furthermore, the lifetime of such wide-area lasers advantageously increases, and they can simultaneously have a beam profile optimized for the respective application. In addition, the wide-band laser according to the invention advantageously makes it possible to set the emission characteristic specifically between forward radiation, Gaussian profile and rectangular profile or mixtures thereof.

• Einzelemitterdichte, insbesondere einstellbar über den jeweiligen Abstand der Stege,
• Laserschwellströme, beispielsweise durch Steuerung der Stromaufweitung über Indexführung und/oder eine unterschiedliche Breite der einzelnen Stege, und
• Steilheit, beispielsweise durch Steuerung der Verluste,
• oder Kombinationen hieraus.

In particular, by means of such a wide-band laser, it is possible to form the emission characteristic in a targeted manner by means of a controlled control of the

• Single emitter density, in particular adjustable over the respective distance of the webs,
• Laser Schwellströme, for example, by controlling the flow expansion over index guide and / or a different width of the individual webs, and
• Steepness, for example by controlling the losses,
• or combinations thereof.

The broad-band laser, in particular the epitaxial layer stack of the broad-band laser, is preferably based on InGaN, particularly preferably on InGaAlN. Preferably, the wide stripe laser is an edge emitter. Preferably, the wide stripe laser is a semiconductor laser.

In a preferred embodiment of the wide-band laser, at least one layer of the layer stack is n-doped on the underside facing side of the active radiation-generating layer and at least one layer of the layer stack is p-doped on the side of the active, radiation-generating layer facing the upper side.

All layers of the layer stack are preferably n-doped or undoped on the side of the active, radiation-generating layer facing the underside, and all layers of the layer stack are p-doped or undoped on the side of the active, radiation-generating layer facing the top side.

The trenches of the wide-band laser are preferably formed in the p-doped layer or the p-doped layers of the layer stack.

Preferably, the trenches do not penetrate the active layer of the layer stack of the wide-band laser. In this case, the trenches are thus formed only on the upper side of the layer stack.

Alternatively, the trenches can penetrate the active layer. In this case, the trenches in all layers of the Layer stack, which are located on the top side facing the active radiation-generating layer, and formed in the active, radiation-generating layer.

Preferably, the webs each have a same height.

In a preferred embodiment of the wide-band laser, the trenches each have an equal depth. Alternatively, the trenches may at least partially have a different depth.

For example, the trough depth between the lands is less than outside the original latitude strip. As a result, the stronger facet load of the middle webs can be counteracted by a higher current widening. Preferably, the depth difference of the trenches is step-shaped.

Alternatively, the index-defining trough depth between the lands may be higher than outside the original wide-strip. As a result, the beam profile of the wide-band laser can be controlled with advantage over the depth-dependent steepness of the trenches.

In a preferred embodiment of the wide-band laser adjacent webs are each arranged at an equal distance from each other.

Alternatively, adjacent webs may be at least partially disposed at a different distance from each other. Preferably, adjacent inner webs have a greater distance from each other than adjacent outer webs. Thereby can be counteracted the different thermal load of the webs.

In a preferred embodiment of the wide-band laser, the webs at least partially have a different width.

Preferably, inner webs have a greater width than outer webs. This can be counteracted a different oscillation, which is due in particular by a different thermal load, whereby the beam profile is influenced with advantage targeted.

In the wide-stripe laser, the trenches each have a base surface, each having a curvature. The depth difference of the trenches is preferably gradual. Thus it can be counteracted with advantage of the stronger facet load of the middle webs by a higher current widening.

The curvatures of the bases of the trenches are preferably lenticular. Preferably, the bases of the trenches together form a convex lens shape.

In a preferred embodiment of the wide-band laser, a connection layer is arranged at least in some areas on the webs.

By way of example, the connection layer can completely cover a side of the webs facing away from the active layer. Alternatively, the connection layer may be structured on the webs in each case.

Preferably, the connection layer is formed on the webs in each case as a connection layer withdrawn from two mutually opposite edges of the layer stack. Furthermore, the connection layer on the webs can each be designed as a connection layer provided with one or more openings. The openings of the connection layer may extend transversely to the respective web or along the respective web. This allows specific areas with higher absorption can be generated.

In regions of the openings of the connection layer, in a further preferred refinement of the wide-area laser, further trenches may be arranged which extend in regions vertically into the respective webs, but which do not completely penetrate them.

In a further preferred embodiment of the wide-band laser, a passivation layer is arranged in regions between the webs and the connection layer. The passivation layer is preferably designed to be electrically insulating. In areas of the passivation layer, there is thus no electrical contact between the layers of the webs and the connection layer. The connection layer can be formed over the entire surface, wherein the electrical connection between the connection layer and the layer stack is not formed over the entire surface due to the passivation layer.

Preferably, a dielectric passivation is arranged on the upper side of the epitaxial layer stack, wherein no dielectric passivation is arranged on the webs. In areas on the jetties, the Dielectric passivation thus each have a recess. Preferably, the dielectric passivation is formed as a layer.

The passivation layer and / or the dielectric passivation preferably contain silicon dioxide (SiO ₂ ), silicon nitride (SiN), aluminum oxide (Al ₂ O ₃ ), hafnium oxide (HfO ₂ ), zirconium oxide (ZrO ₂ ) or tantalum oxide (Ta ₂ O ₅ ).

In a further preferred embodiment, a plurality of wide-band lasers are arranged side by side as separate arrays, wherein the distances between adjacent arrays are each preferably greater than 20 microns.

In a further preferred embodiment of the wide-band laser, an optical lens or a lens system is arranged downstream of the laser in the emission direction. A wide-band laser according to the invention, which has a controlled emission characteristic, can advantageously be combined with an optical lens or a corresponding lens system in such a way that a desired imaging property is achieved.

• a) Epitaktisches Aufwachsen eines Schichtenstapels auf einem Aufwachssubstrat, wobei der Schichtenstapel eine Oberseite und eine Unterseite aufweist,
• b) Oberseitiges Ätzen des Schichtenstapels an zwei sich gegenüberliegenden Kanten des Schichtenstapels derart, dass eine Breitstreifenlaserstruktur ausgebildet wird, und
• c) Oberseitiges Ätzen von Gräben in den Schichtenstapel im Bereich der Breitstreifenlaserstruktur derart, dass Stege ausgebildet werden, die jeweils eine Breite von höchstens 20 µm, bevorzugt von höchstens 10 µm aufweisen, wobei benachbarte Stege einen Abstand von höchstens 20 µm, bevorzugt von höchstens 10 µm zueinander aufweisen.

A method according to the invention for producing a wide-band laser comprises in particular the following steps:

• a) Epitaxially growing a layer stack on a growth substrate, wherein the layer stack has a top side and a bottom side,
• b) top etching the layer stack on two opposite edges of the layer stack such that a wide stripe laser structure is formed, and
• c) top etching of trenches in the stack of layers in the region of the broad strip laser structure such that webs are formed, each having a width of at most 20 .mu.m, preferably of at most 10 .mu.m, wherein adjacent webs a distance of at most 20 .mu.m, preferably of at most 10th Have each other.

The conventionally known wide-stripe laser structure is split in particular into individual strips, in particular individual webs. By a different width of the webs and / or by a different index guide of the beam profile, the output power can be optimized for the particular application of the laser out. Thus, an improved optical output, improved radiance and increased lifetimes, in particular a simultaneously controllable optimization of the beam profile is made possible.

Figuren 1, 3, 4, 8, 10, 11 und 12

jeweils einen schematischen Querschnitt einer Abwandlung eines Breitstreifenlasers,

Figur 6

einen schematischen Querschnitt eines Ausführungsbeispiels eines erfindungsgemäßen Breitstreifenlasers,

Figuren 2, 5 und 9

jeweils ein Herstellungsverfahren zur Herstellung einer Abwandlung eines Breitstreifenlasers,

Figur 7

ein erfindungsgemäßes Herstellungsverfahren zur Herstellung eines Ausführungsbeispiels eines Breitstreifenlasers, und

Figur 13A bis 13C

jeweils eine Aufsicht auf ein Ausführungsbeispiel eines Steges eines erfindungsgemäßen Breitstreifenlasers.

Further features, advantages, preferred embodiments and expediencies of the wide-band laser and the method for its production will become apparent from the following in connection with the FIGS. 1 to 13 explained embodiments. Show it:

FIGS. 1, 3, 4, 8, 10, 11 and 12

each a schematic cross section of a modification of a wide-band laser,

FIG. 6

a schematic cross section of an embodiment of a wideband laser according to the invention,

FIGS. 2, 5 and 9

each a manufacturing method for producing a modification of a wide-band laser,

FIG. 7

an inventive manufacturing method for producing an embodiment of a wide-band laser, and

FIGS. 13A to 13C

in each case a plan view of an embodiment of a web of a wide-band laser according to the invention.

Identical or equivalent components are each provided with the same reference numerals. The components shown and the size ratios of the components with each other are not to be considered as true to scale.

In FIG. 1 FIG. 3 shows a schematic cross-section of a modification of a wide-band laser comprising an epitaxial layer stack 2 with an active radiation-generating layer 21. In particular, the layer stack 2 has an upper side 22 and a lower side 23. The layer stack 2 may be arranged, for example, on a substrate or a carrier (not shown).

Preferably, the layers facing the underside 23 have an n-doping seen from the active layer 21. The layers of the layer stack 2, that of the top 22 facing from the active layer 21, preferably have a p-type doping. For example, magnesium or zinc can be used as p-doping.

The laser is designed in particular as a wide-band laser 1. In this case, the laser structure is etched so that a narrow strip is formed on the upper side, whereby there is advantageously a strong index guiding by the refractive index jump of the laser structure to air.

In the modification to FIG. 1 In particular, the p-doped layers of the wide-band laser are removed down to a narrow strip, whereby the electrons are laterally restricted and diffusion is avoided.

The layer stack 2 also has trenches 3, in which at least one layer of the layer stack is at least partially removed and which lead from the top side 22 in the direction of the bottom side 23. The wide-strip laser 1 thus has further etching areas on the upper side, wherein the wide strip of the laser structure is split into individual strips, so-called webs. The layer stack 2, in particular the wide strip of the wide-band laser 1, is thus strip-shaped on the upper side.

The webs 4 preferably have a width of at most 20 .mu.m, preferably of at most 10 .mu.m, more preferably of at most 7 .mu.m. The trenches 3, which separate adjacent webs 4 from one another, each have a width of at most 20 .mu.m, preferably of at most 10 .mu.m. Thus, adjacent webs 4 each have a distance of at most 20 .mu.m, preferably of at most 10 .mu.m to each other.

By splitting the wide stripe of the laser into webs 4, the beam profile and the output power can advantageously be optimized for the particular application of the laser. In particular, the optimization can be achieved by means of a different web width and / or a different index guide.

The wide-band laser 1, whose wide strip is divided into webs 4, advantageously allows improved optical output power, improved radiance, and extended life. In particular, a controllable optimization of the beam profile is possible at the same time. Furthermore, the efficiency increases at high power with advantage.

In particular, the emission characteristic of such a wide-band laser can be specifically shaped by, for example, controlled control of the single emitter density (distance of the webs), the laser threshold currents (for example, by controlling the current spread over the index guide and / or over the different land width of the individual emitter), and / or the slope ( for example via loss control) or combinations thereof.

Preferably, the in FIG. 1 Wide strip laser 1 shown an edge emitter.

The trenches 3 of the wide-band laser 1 are produced, for example, by means of an etching process. The etching depth T ₁ in the embodiment of the FIG. 1 is in particular designed such that the active layer 21 is not etched, in particular no trenches 3 through the active layer 21 are guided. Alternatively, the trenches 3 may penetrate the active layer 21 (not shown).

In the modification of the FIG. 1 the trenches 3 each have an equal depth T ₁ . The trench width d ₂ is at most 20 μm. In particular, the distance between two adjacent webs 4 is at most 20 μm. The webs 4 have a width d ₁ of at most 20 microns, preferably 10 microns.

On the upper side 22 of the layer stack 2, a dielectric passivation 9 is preferably arranged, wherein on the webs 4 no dielectric passivation 9 is arranged. In regions on the webs 4, the dielectric passivation 9 thus each has a recess. Preferably, the dielectric passivation 9 is formed as a layer.

The dielectric passivation 9 preferably contains silicon dioxide (SiO ₂ ), silicon nitride (SiN), aluminum oxide (Al ₂ O ₃ ), hafnium oxide (HfO ₂ ), zirconium oxide (ZrO ₂ or tantalum oxide (Ta ₂ O ₅ ).

In the other FIGS. 2 to 13 the dielectric passivation 9 is not shown for the sake of clarity. However, the dielectric passivation 9 also finds in the other FIGS. 2 to 13 Application, even if not explicitly shown.

On the webs 4 each have a connection layer 5 is arranged. In the modification of the FIG. 1 the connecting layer 5 completely covers the side of the webs facing away from the active layer 21 in each case. The connection layer 5 is thus preferably in each case in the recesses of dielectric passivation 9 arranged. The connection layer 5 is preferably like the webs 4 strip-shaped, wherein the connection layer 5 in the modification of FIG. 1 is formed in each case in areas of the webs as a continuous layer. Preferably, the connection layer 5 has no recesses or openings on the webs.

Through the connection layer 5 as well as through the webs 4, the trenches 3 are guided. The connection layer 5 is thus formed as a structured, in particular strip-shaped connection layer, the strips of the connection layer 5 coinciding with the webs 4. In particular, only the side of the webs 4, which faces away from the active layer 21, has the connection layer 5.

The connection layer 5 preferably comprises a metal or a metal alloy.

The broadband laser of the modification of the FIG. 1 allows an increased optical output power or output line density, the facet load of the laser is reduced, the lifetime is increased with advantage and at the same time an optimized for each application beam profile is enabled. In particular, such a broadband laser designed in this way makes it possible to set the emission characteristic specifically between forward radiation, Gaussian profile and rectangular profile or mixtures thereof.

Preferably, such wide stripe lasers having a controlled emission characteristic can be used in combination with lenses (not shown). Especially can be achieved with an optical lens or a corresponding lens system, a desired imaging property.

In the FIGS. 2A and 2B are each manufacturing steps for producing a wide-band laser according to the modification of FIG. 1 shown. In particular shows FIG. 2A a conventional wide-stripe laser, in which the layer stack 2 is removed on the upper side 22 such that the upper side, a wide strip is formed.

Preferably, the wide strip is formed by means of a first etching process. In this case, the active layer 21 of the wide-band laser is preferably not etched.

On the upper side, the layer stack 2 has a connection layer 5 for electrical contacting of the wide-area laser. On the underside, a substrate or a support may be arranged (not shown), wherein on the underside for the electrical contacting of the wide-area laser preferably a further connection layer is arranged (not shown).

Following the production of the wide-strip laser structure, trenches 3 are etched in the wide strip arranged on the upper side, so that the wide strip is split or divided into webs 4, see FIG FIG. 2B , The webs 4 preferably have a width d ₁ of at most 20 .mu.m, more preferably of at most 10 .mu.m. The etching width, that is to say the trench width d ₂ , preferably has at most 20 μm, preferably at most 10 μm. Two adjacent webs 4 are therefore in particular thus arranged at most at a distance of 20 μm, preferably of at most 10 μm, from each other. The etching depth T _{1 of} the individual trenches 3 is in the Embodiment of Figures 1 and 2 each about the same size. In particular, the etching depth T _{1 is formed} such that the active layer 21 of the wide-band laser is not penetrated or etched.

The conventionally known wide-stripe laser structure is thus in the modification of FIG. 2 split into a plurality of equal width, equidistant, deeply etched webs 4 by means of a further etching process.

Alternatively, the production of the wide strip and the production of the webs 4, ie the respective etching processes, can be carried out in one etching step.

The modification of FIG. 3 is different from the modification of FIG. 1 in that adjacent webs 4 are at least partially arranged at a different distance from each other. Preferably, adjacent inner webs 4a have a greater distance from each other than adjacent outer webs 4b. The distance of the webs 4a, 4b to each other, however, has at most 20 microns, preferably 10 microns. Due to the different distances of adjacent webs 4a, 4b, the different thermal load can be counteracted. This advantageously increases the service life of such a broadband laser.

The modification of FIG. 4 is different from the modification of FIG. 1 in that the trenches 3 have a smaller etching depth T ₁ in the broad-band structure of the laser. In particular, the trenches 3 do not completely penetrate the broad stripe structure of the laser. The depth T _{2 of} the broad-band structure of the laser is therefore greater than the depth T _{1 of} the trenches 3.

The wide-strip structure is thus split into a plurality of equidistant, equidistant webs 4, wherein the index-defining etch depth T ₁ between the webs 4 is less than outside the original wide stripe to counteract the stronger facet load of the middle webs by a higher current widening. The Ätztiefenunterschied T ₁ to T ₂ preferably runs in steps.

In the FIGS. 5A to 5D are individual manufacturing steps for producing a wide-band laser according to the modification of FIG. 4 shown.

In FIG. 5A a layer stack 2 comprising an active radiation-generating layer 21, an upper side 22 and a lower side 23 is shown. At the top 22, as in FIG. 5B represented, formed by means of a first etching process, a wide strip structure. The etches preferably do not pass through the active layer 21. The first etching step takes place in particular by means of a photoresist 6 which is formed on the upper side 22 of the laser.

Alternatively, the first etching step instead of the photoresist by means of an etch mask, which is formed on the upper side 22 of the laser. The etching mask may be, for example, a dielectric or metallic hard mask.

In a further etching process, trenches 3 are etched into the wide stripe structure, as in FIG FIG. 5C shown. In this case, the etching depth of the trenches 3 is less than the etching depth of the wide strip structure in this case.

Alternatively, the production of the wide strip and the production of the webs 4, in particular the first etching process and the further etching process can be carried out in one etching step.

In the last step, as in FIG. 5D represented, the photoresist 6 is removed, wherein on the webs 4, a connection layer 5 is arranged.

The embodiment of FIG. 6 is different from the modification of FIG. 4 in that the trenches 3 each have a base 31, which in each case has a curvature. The curvature of the base 31 is preferably formed in each case lens-shaped. In particular, the curvatures of the base surfaces 31 together have a convex lens shape.

The trenches 3 thus have in the embodiment of FIG. 6 a different depth. In particular, the wide-strip structure is split into a plurality of equidistant, equidistant webs 4, wherein the index-defining etch depth between the webs is less than outside the original wide stripe, to counteract the stronger facet load of the middle webs by a higher current expansion. The etch depth difference in this case is preferably gradual.

In the FIGS. 7A to 7D are manufacturing steps of a wide-band laser according to the embodiment of FIG. 6 shown.

As in FIG. 7A 1, an etching auxiliary mask 8 is applied to the layer stack 2, in particular on the upper side 22 of the layer stack 2. On the Ätzhilfsmaske 8 a photoresist 7 is arranged, which preferably flows through a thermal treatment. Due to the flowing photoresist, a lenticular structure of the etching auxiliary mask can be produced. In particular, the etching aid mask is thus structured in a lens-shaped manner, as in FIG FIG. 7B shown. This structuring is preferably carried out by means of a dry chemical transfer to the etching auxiliary mask 8.

In the next step, as in FIG. 7C shown, a strip-shaped paint structure 6 applied to the lens-shaped etching auxiliary mask 8. Subsequently, by means of a further etching process, a single stripe structure with a graded index guide is formed, as in FIG Figure 7D shown. In particular, webs 4 and trenches 3 are formed in the layer stack 2 on the upper side, wherein the trenches 3 have a base surface 31, each having a curvature.

The modification of FIG. 8 is different from the modification of FIG. 4 in that the trenches 3 have a greater depth, in particular a larger etching depth T ₁ , than the broad-band structure of the laser (depth T ₂ ). In particular, the wide-strip structure is split into a plurality of equidistant, equidistant webs 4, wherein the index-defining etching depth T ₁ between the webs 4 is gradually or stepwise higher than outside the original Breitstreifens, which can be controlled by the Ätzeniefenabhängige steepness with advantage targeted the beam profile of the laser.

In the FIGS. 9A to 9D are each manufacturing steps for producing a wide-band laser according to the modification of FIG. 8 shown.

Similar to the modifications of the FIGS. 5A to 5D In this case, a multi-stage etching process is used. On the layer stack 2, a photoresist 6 is applied in the edge region, see FIG. 9B , where here a first etching process takes place, which forms a first etching region 9 on the upper side of the layer stack 2. Subsequently, a strip-shaped lacquer structure is applied to the upper side 22 of the layer stack 2 in regions of the first etching process 9, with a second etching process subsequently taking place, which etches trenches 3 into the upper side 22 of the layer stack 2. In this case, the trenches 3, in contrast to the modification of FIGS. 5A to 5D etched so deeply that the etch depth T _{1 is} higher than the etch depth T _{2 of} the wide stripe structure, see FIG. 9C , In the next method step, the strip-shaped lacquer structure 6 is removed, wherein a connection layer 5 is applied in each case to the webs 4, see FIG. 9D ,

The modification of FIG. 10 is different from the modification of FIG. 1 in that the webs 4 have a different width b ₁ , b ₂ . Inner webs preferably have a larger width b ₁ than outer webs (width b ₂ ).

The broadband laser according to the modification of FIG. 10 thus has a plurality of equidistant, deep etched, different width webs 4, whereby a different oscillation, which is due to a different thermal load, can be counteracted with advantage. As a result, the beam profile of the laser can advantageously be influenced in a targeted manner.

The modification of FIG. 11 is different from the modification of FIG. 1 in that the connection layer 51, 52, which is respectively arranged on the webs 4, is structured. In particular, the terminal layer 51, 52, in contrast to the in FIG. 1 shown connection layer guided along the respective web 4 opening 5c. Accordingly, the connection layer 51, 52 on the respective webs 4 is strip-shaped, in which case the connection layer 51, 52 has two strips 51, 52 arranged laterally on the webs 4. Between the strips 51, 52, the opening 5c of the connection layer is formed, so that no connection layer 51, 52 is arranged in regions on the webs 4, in particular in the middle region of the webs 4.

The connection layer 51, 52 is thus preferably composed of profit-guided strips, in particular metallization strips.

A view of such a trained connection layer is, for example, in FIG. 13C shown. The web 4 has laterally two connection layers 51, 52, which are guided along the web 4 and in particular are pulled through. No connection layer is arranged centrally along the web 4.

The modification of FIG. 12 is different from the modification of FIG. 11 in that the webs in regions, in particular in the areas in which no connection layer 5 is applied, have further etching depths. The connection layer 5 is in particular arranged in each case on a lateral region of the webs 4, so that the further etching depths are formed centrally of the webs 4. In particular, the etching depths do not lead completely vertically through the webs 4.

In the embodiments of the FIGS. 13A to 13C in each case a plan view of a web 4 is shown. In particular, the embodiments of the show FIGS. 13A to 13C in each case additional modifications of the connection layer 5.

In FIG. 13A the connection layer 5 is formed as a not completely drawn through connection layer. In particular, the connection layer 5 is formed on the webs 4 in each case as a connecting layer 5 which is drawn back from two mutually opposite edges 5a, 5b of the webs 4. The webs 4 therefore have no connection layer 5 in the edge region 5a, 5b. This allows specific areas with a higher absorption can be generated.

The embodiment of FIG. 13B differs from the embodiment of FIG. 13A in that the connection layer 5 has openings 5c. In particular, the connection layer 5 has a plurality of openings 5c transversely to the web 4.

In contrast, the embodiment of the FIG. 13C an opening 5c along the web 4. The connection layer 5 is therefore split into two strips 51, 52, which extend along the web 4.

As an alternative to a connection layer 5, which has openings 5c, a passivation layer may be arranged between the connection layer 5 and the webs 4 (not shown). The passivation layer is in particular electrically insulating, so that the connection layer 5 can be formed over the entire surface, wherein the electrical contact between the connection layer 5 and the bridge 4 is not formed over the entire surface by means of the passivation layer. In particular, in areas of the passivation layer no electrical contact between the connection layer 5 and the web 4 takes place. For example, the passivation layer contains silicon dioxide (SiO ₂ ), silicon nitride (SiN), aluminum oxide (Al ₂ O ₃ ), hafnium oxide (HfO ₂ ), zirconium oxide (ZrO ₂ ) or tantalum oxide (Ta ₂ O ₅ ).

Furthermore, a plurality of wide-band lasers according to the embodiments of the broad-band laser of FIGS. 1 . 3 . 4 . 6 . 8th . 10, 11 or 12 arranged side by side as a separate arrays, wherein the distances between adjacent arrays are each preferably greater than 20 microns (not shown).

Claims (15)

1. A broad stripe laser (1) comprising an epitaxial layer stack (2), which contains an active, radiation-generating layer (21) and has a top side (22) and an underside (23), wherein

   - the broad stripe laser (1) has a broad stripe structure having a broad stripe arranged on the top side,

   - the layer stack (2) has trenches (3) in which at least one layer of the layer stack (2) is at least partly removed and which lead from the top side (22) in the direction of the underside (23),

   - the layer stack (2) has on the top side ridges (4) each adjoining the trenches (3), such that the layer stack (2) is embodied in striped fashion on the top side, and such that the broad stripe is split into index-guided adjacent individual stripes, the ridges (4),

   - the broad stripe laser (1) is an edge emitter, and

   - the ridges (4) and the trenches (3) respectively have a width (d₁, d₂) of at most 20 µm characterized in that the trenches (3) each have a base area (31) and the base area (31) has a curvature in each case.
2. Broad stripe laser according to Claim 1, wherein
   at least one layer of the layer stack (2) on that side of the active, radiation-generating layer (21) which faces the underside (23) is n-doped and at least one layer of the layer stack (2) on that side of the active, radiation-generating layer (21) which faces the top side (22) is p-doped and the trenches (3) are formed in the p-doped layer or the p-doped layers of the layer stack (2).
3. Broad stripe laser according to either of the preceding claims, wherein
   the layer stack is based on the InGaAlN material system.
4. Broad stripe laser according to any of the preceding claims, wherein
   the trenches (3) penetrate through the active layer.
5. Broad stripe laser according to any of the preceding claims, wherein
   the ridges (4) have a width (d₁) of less than 7 µm and adjacent ridges (4) have a distance (d₂) from one another of at most 10 µm.
6. Broad stripe laser according to any of the preceding claims, wherein
   the trenches (3) have a different depth at least in part.
7. Broad stripe laser according to any of the preceding claims, wherein
   adjacent ridges (4) are in each case arranged at an identical distance from one another.
8. Broad stripe laser according to any of the preceding Claims 1 to 6, wherein
   adjacent ridges (4) are arranged at a different distance from one anther at least in part, wherein adjacent inner ridges (4a) are at a greater distance from one another than adjacent outer ridges (4b).
9. Broad stripe laser according to any of the preceding claims, wherein
   the ridges (4) have a different width (b₁, b₂) at least in part.
10. Broad stripe laser according to any of the preceding claims, wherein
    the base areas (31) of the trenches (3) together form a convex lens shape.
11. Broad stripe laser according to any of the preceding claims, wherein
    a connection layer (5) is arranged at least in regions in each case on the ridges (4).
12. Broad stripe laser according to Claim 11, wherein
    the connection layer (5) is formed on the ridges (4) in each case as a connection layer (5) drawn back from two opposite edges (5a, 5b) of the layer stack (2).
13. Broad stripe laser according to Claim 11 or 12, wherein
    the connection layer (5) is formed on the ridges (4) in each case as a connection layer (5) provided with one or more openings (5c).
14. Broad stripe laser according to any of the preceding Claims 11 to 13, wherein
    a passivation layer is arranged in the regions between the ridges (4) and the connection layer (5).
15. Method for producing a broad stripe laser (1) according to any of the preceding claims, comprising the following method steps:

    - epitaxial growth of a layer stack (2) on a growth substrate, wherein the layer stack (2) has a top side (22) and an underside (23),

    - top-side etching of the layer stack (2) at two opposite edges (24a, 24b) of the layer stack (2) in such a way that a broad stripe laser structure is formed,

    - top-side etching of trenches (3) in the layer stack (2) in the region of the broad stripe laser structure in such a way that ridges (4) are formed, each having a width (d₁) of at most 20 µm, wherein adjacent ridges (4) are at a distance (d₂) from one another of at most 20 µm.

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